The present invention relates to a production management system, and more particularly to a production management system with optimization to schedules for individual stages throughout production schedule planing and actual production management in a production facility to improve a planing reliability with adjustment to loads of individual production facilities as well as planning, management and modification of working performance schedules.
The conventional production management system will be described by taking as an example a standard manufacturing schedule system with reference to FIG. 1 which is a block diagram illustrative of a conventional method of making a conventional standard manufacturing schedule data base.
It will be considered that products and produced in production lines. Actual times taken from a start of the actual production to a completion thereof are collected for a predetermined amount of lots, so that an average processing time (1) per a single lot, an average working preparation time (2) per a single lot, an average carrying time (3) per a single lot and an average waiting time (4) per a single lot are found in a actual time collection step S1.
In consideration of priority, the waiting times are adjusted in a "waiting time adjustment of priority adjustment" step S2, wherein other times than the waiting time are, of course, unchanged and fixed. For example, the waiting times are adjusted in a manner that the priority is risen up to shorten the waiting time whilst the priority is fallen down to postpone the waiting time.
In a "standard manufacturing schedule determination" step S3, a standard manufacturing schedule is so determined that a term of the standard manufacturing schedule is shorter by a margin than a market-demand working term.
In a "standard manufacturing schedule data base registration" step S4, the decided standard manufacturing schedule is registered in a standard manufacturing schedule data base system.
The subsequent descriptions will focus on planning an input schedule and an actual production in production lines with reference to FIG. 2 which is a flow chart illustrative of conventional sequential processes from planing an input schedule through a completion of an actual production in production lines.
In a step S21, a draft production schedule is prepared in accordance with client's orders, wherein the draft production schedule is represented in the form of standard manufacturing schedule bars as illustrated in FIG. 3. There may be omitted the above "standard manufacturing schedule determination" step S3 and the above "standard manufacturing schedule data base registration" step S4.
Referring back to FIG. 2, in a step S22, assuming that the productions are made in accordance with the draft production schedule, load summation calculations are made for each equipment or group for every date. FIG. 4 is a view illustrative of individual loads to individual equipments over dates with reference to individual production capacity possessed by the individual equipments.
In a step S23, there is confirmed whether or not the individual loads to individual equipments over dates are beyond individual production capacity possessed by the individual equipments. If the individual loads remain below the individual production capacity possessed by the individual equipments, then this means it possible to realize the draft production schedule. If, however, the individual loads are made beyond at least any one day the individual production capacity possessed by the individual equipments, then this means it difficult to realize the draft production schedule.
In a step S24, the above original draft production schedule is corrected so as to satisfy the conditions of the client's designated delivery date. FIG. 5 is a view illustrative of a corrected draft production schedule represented in the form of standard manufacturing schedule bars.
The step will be back to the step S22, assuming that the productions are made in accordance with the corrected draft production schedule, load summation calculations are made for each equipment or group for every dates. FIG. 5 is a view illustrative of individual loads to individual equipments over dates with reference to individual production capacity possessed by the individual equipments.
Again in the step S23, there is confirmed whether or not the individual loads to individual equipments over dates are beyond individual production capacity possessed by the individual equipments. If the individual loads remain below the individual production capacity possessed by the individual equipment, then this means it possible to realize the draft production schedule. If, however, the individual loads are made beyond at least any one day the individual production capacity possessed by the individual equipments, then this means it difficult to realize the draft production schedule.
The above looped processes of the steps S22, S23 and S24 will be repeated until all of the individual loads to individual equipments over dates are below the individual production capacity possessed by the individual equipments.
In a step S25, an actual production process will start and in a subsequent step S26, the individual summation loads are set targets for the individual equipments or groups so as to check in a predetermined time span such as one time per one day whether or not the individual targets are achieved by the individual equipments or groups. If the target is not achieved, then in a step S27, a production speed is accelerated to recover the delay and attempt to achieve the target.
The closet prior art to the above conventional production management system is disclosed in Japanese laid-open patent publication No. 6-259436.
The above conventional production management system has the following disadvantages. The conventional production management system is free of any feature of planing the production schedule or the production target together with recognition of an urgently achieved load or target which should be completed within this month from a non-urgently achieved load or target which may be completed by the next mouth or later. Further, the conventional production management system is free of any feature of correcting the production target and accelerating the production speed under management of both the urgent and non-urgent loads or targets. Those raise the following problems.
The conventional system is incapable of recognizing which lot may raise a problem like that since a production of this lot had a low priority in the past, the production of this lot has been discontinued under the priority management even the production should have to be completed within this month. This means that the priority management is necessary condition, but not sufficient condition. Namely, only the priority management is insufficient.
Under the priority management, only high priority lots are processed by taking precedence over the low priority lots whereby the individual loads to the individual equipments may be unbalanced. As a result, the timing of beginning the productions of the lots may be unbalanced.
The problem with unbalance in loads may raise a further serious problem that although all individual targets allocated for the individual equipments or groups are achieved, any of the lots which should have to be completed within this month could not arrive at this month target, resulting in that a monthly production target could not be achieved.
Furthermore, in recent years, the requirement for shortening the production delivery term of the custom products has been on the increase due to market unpredictability.
For the production of the custom products, there is raised a problem in postponing the delivery data of the products from the client's designated data. The production line for this client is stopped. As a result, customer's reliance has been lost and not further order could be received from this client.
The conventional system is, however, incapable of distinguish the urgently achieved load or target which should be achieved within this month from the non-urgently achieved load or target which should be achieved by the next month or later, for which reason the conventional system makes it difficult to investigate the cause of the unachievement and to take countermeasure against the above problem.
Even if the production speed is accelerated and this month target could be achieved, then in the next or later months, the above problems may be raised repeatedly.
In the above circumstances, it had been required to develop a novel production management system free from the above problems.